1. Field of the Invention
This invention relates to systems for mixing and dispensing concrete. More specifically, this invention relates to chutes for guiding concrete from the discharge end of a concrete mixer to a desired location.
2. Description of the Prior Art
Concrete mixing trucks, such as those manufactured by the assignee of this invention, McNeilus Truck and Manufacturing Corporation of Dodge Center, Minn., are widely used in the construction industry for preparing and transporting a concrete mixture to a desired construction site.
In order to guide concrete into a set of forms or equivalent molding structure, most mixing trucks in commercial use today include a collector into which the discharged concrete is accumulated prior to deposit onto the chute system, a pivotable main discharge chute, a second chute, known as a fold-out chute, which folds out from the main chute, and, optionally, an extension chute which connects to the fold-over chute and/or additional extension chutes which connect to one another for extending the chute system.
In order to withstand the stress and abrasion created by the flux of wet concrete, discharge chute components need to possess a great deal of strength and wear resistance. At present, manufacturers have relied upon thick gauge sheet metal to construct chute components with the necessary strength and wear characteristics. Metal chute components have proven effective in guiding concrete. However, their weight makes the chute assembly difficult to assemble, disassemble and reposition.
Another disadvantage with metal discharge chute components is their tendency to oxidize or otherwise corrode after prolonged use. This type of degradation, in conjunction with normal abrasive wear, can cause the guide surfaces of chute components to become roughened, thereby impairing their efficiency for guiding and making it more difficult to clean the guide surfaces after use.
Another problem which is present in existing discharge chute assemblies involves the connections which are used to join extension chutes to each other and to upstream chutes. Most existing systems use a simple hook-loop type connection to make such a connection. Such connections, however, tend to become jammed with wet concrete, which eventually hardens. In addition, clothing can be caught on the sharp hooks and other edges of such joints. Furthermore, prior art joints are often difficult to fasten and release, particularly by a single person.
It is clear that there has existed a long and unfilled need in the art for a discharge chute component which is lighter in weight, less susceptible to roughening of its guide surfaces, and provides a safer and more reliable joint structure than chute components heretofore known, without any significant loss in strength and/or wear resistance.